1. Field of the Invention
The present invention relates to an image forming apparatus, and more particularly, to a configuration of developing unit of an image forming apparatus.
2. Description of the Related Art
Developing units employed in compact image forming apparatuses such as laser printers may include an internal space for housing developer, a photosensitive medium, a developer supply unit for supplying developer and a waste developer collecting portion for collecting remaining developer, all of which are integrated as a single cartridge.
Due to such integration, despite the fact that the other components of the developing unit, e.g., photosensitive media and developer supply units, may have considerable remaining useful life, when developer is completely exhausted, a user needs to replace the entire developing unit with a new one at least in part due to the difficulties in only replenishing the developer by the user.
To avoid the cost of new developing unit, users may attempt to refill a used developing unit with additional supply of developer or to purchase from so called recycling vendors a used developing unit that has been refilled with developer. However, these refilling attempts are generally inadequate, as they are messy and may result in damage or reduced performance of the developing units if developer of inferior quality is used as replenishment.
Researches are on-going among the manufacturers of image forming apparatus to provide ways in which to allow replenishment of genuine quality developer by the users.